The present invention is directed to spray guns, and more particularly to spray guns used to spray a mixture of two or more fluids.
Spray guns are often used in fiberglass component manufacturing processes that spray a substrate or component with a liquid resin material. As is known in the art, many liquid resins used in spray coating processes involve mixing resin with a catalyst that initiates polymerization in the resin. Once this mixture is sprayed onto the substrate, the resin continues to polymerize until it sets and hardens.
To control the flow of this mixture, spray guns often include a valve body having a valve control unit in front of a mixing chamber. Both the valve body and the mixing chamber need to be periodically flushed during routine maintenance. Because the resin and catalyst are mixed well before the mixture is sprayed out of the gun, however, the mixture begins to polymerize inside the mixing chamber and the valve body. This early polymerization causes the mixture to leave a film inside the mixing chamber and the valve body as it travels through the gun before it is sprayed out. This film often cannot be completely removed during the flushing process, making it necessary to replace spray gun components on a regular basis as they become clogged with hardened resin residue.
Further, existing spray guns contain a large number of parts and seals that potentially leak, decreasing the reliability of the gun as well as increasing manufacturing costs. Also, currently used spray guns often have relatively small fluid channels, which encourage high fluid velocity of the resin mixture as it travels through the spray gun. However, the high fluid velocity tends to cause internal wear within the channels, requiring increased maintenance and part replacement.
There is a desire for a spray gun that avoids the leakage and maintenance problems experienced by currently known spray guns.
Accordingly, the present invention is directed to a spray gun having a valve body and a manifold that each contain two channels to keep two different fluids separated from each other. The channels in the manifold converge at a vertex, directing the two different fluids to impinge each other inside the manifold. In one embodiment, the manifold directs a catalyst and a resin to impinge immediately before they are sent to a mixer, where they are mixed together more thoroughly before being sprayed out of the gun. By keeping the catalyst and resin separate and mixing them just before they are output, the inventive structure prevents buildup of a polymerized resin film inside the valve body and manifold and ensures that the manifold can be completely cleaned during a flushing process.
Other embodiments of the spray gun incorporate a static mixer that mixes the two fluids together, a removable spray tip held onto the spray gun with a tip holder, and/or rigid seals disposed on the manifold. The inventive structure therefore minimizes the total number of parts in the spray gun and configures the existing parts to minimize the amount of maintenance they require.